I am new here,I am a linux/unix administrator for a small group of companies with about 8 offices located in different states(1 office is in another country).

My boss has asked me to research and implement a virtual pbx system like http://www.virtualpbx.com or http://www.grasshopper.com(I had initially suggested we use their service which came back and bite me,now he wants me to implement a similar system in house as I am always raving about linux and opensourse and its advantages)

Can I build such a system using asterisk and if it can be done can you please direct me to a how-to or appropriate

2. to install a distro (like Trixbox,Elastix,PBX in a Flash) - pros: you will have a configured a functional system very fast - cons: you have to deal with pre-configured systems and learn how to customize it for your specific needs (if any)Docs:

technow wrote:I can install (OS,Asterisk,FreePBX) configure it and all my offices will be able to use the system even though they are not in the same location

If you use properly configured or supported hardware/software, yes- this is fairly basic.

I presume other offices will be able to access it on the internet to set up new extensions,phone numbers etc.

Depends on what you mean by "access." In the sense that a properly configured client device will be able to connect to your Asterisk server, yes- your other offices will be able to "access" it. Adding new extensions/phone numbers/clients/devices requires administrator-level privileges on your Asterisk server, but can be changed or added from anywhere via SSH.

technow wrote:is there any specific how-to I can follow to create a bare minimum system?

If I were you, I would download/read the Asterisk: The Future of Telephony, 2nd Edition e-book to learn on how to configure/maintain/operate a plain-vanilla Asterisk PBX system. I had done that and am proud of my Asterisk PBX system hosted on a discontinued Netgear WGT634U device flashed with a self-built OpenWRT firmware.

I presume other offices will be able to access it on the internet to set up new extensions,phone numbers etc.

Depends on what you mean by "access." In the sense that a properly configured client device will be able to connect to your Asterisk server, yes- your other offices will be able to "access" it. Adding new extensions/phone numbers/clients/devices requires administrator-level privileges on your Asterisk server, but can be changed or added from anywhere via SSH.

I am a bit confused,maybe because I don't know how this thing will work.

What I am after is a virtual pbx system which can be used by all our offices with a frontend like grashhopper.com minus the payment

What kind od client device will I need to install at the other offices?

client calls landline number for office x --- gets a greeting "Welcome to office x please dial required extension or dial 1 for sales , 2 - for support, etc," --- if client dials extension he/she is transferred to the extension number --- if not then the phone is forwarded to a receptionist

client calls my bosses mobile number --- gets greeting "welcome to boss man from office x he is not available right now please leave a message "

technow wrote:client calls landline number for office x --- gets a greeting "Welcome to office x please dial required extension or dial 1 for sales , 2 - for support, etc," --- if client dials extension he/she is transferred to the extension number --- if not then the phone is forwarded to a receptionist

AFAIK, what you explain above is plainly an IVR (Interactive Voice Response) system that an Asterisk PBX system can easily do. The e-book I mentioned in my previous post will explain how to achieve this easily.

client calls my bosses mobile number --- gets greeting "welcome to boss man from office x he is not available right now please leave a message "

Probably, this feature has nothing to do with an Asterisk PBX system, but rather a feature provided by the voicemail system from a cellphone package. However, if the cellphone has a feature to forward incoming calls to another phone or to a SIP address, then you can have an Asterisk PBX system to greet the caller through its IVR system.

and a similar system for other offices but with different numbers

For a centralized system, you can setup ATA devices on other offices to register to your Asterisk PBX system as extensions, too. Or, you can configure each office to have its own Asterisk PBX system and then peer them. The later is a decentralized system. If you want Asterisk PBX system to bridge to each local PSTN/cellphone lines, then you will need a TDM card with FXO ports on each Asterisk PBX system.